CARBOHYDRATE/PROTEIN CREAM SUBSTITUTES BACKGROUND OF THE INVENTION
The present invention relates generally to non-fat and reduced-fat products which possess the organoleptic characteristics of full fat-contaiiiing products. More specifically, the invention relates to cream substitutes which comprise a core of carbohydrate surrounded by a shell of protein.
Singer et al., U.S. Patents Nos. 4,734,287 and 4,961,953 disclose a proteinaceous, water-dispersible, macrocoUoid comprising substantially non- aggregated particles of dairy whey protein and other proteins. The particles have mean diameter particle size distributions in a dried state ranging from about 0.1 microns to about 2.0 microns, with less than about 2 percent of the total number of particles exceeding 3.0 microns in diameter. Singer et al., U.S. Patent No. 4,828,396 disclose fluid processing devices including means for generating toroidal flow in a fluid to be processed. The devices are capable of cooking under high shear rates and are useful for producing macrocolloids for use as fat substitutes.
Singer et al. , U.S. Patent No. 4,855,156 disclose non-fat and reduced fat whipped frozen desserts wherein part or all of the fat or oil ordinarily incorporated therein is replaced by a proteinaceous macrocoUoid comprising denatured whey protein particles. Singer et al., U.S. Patent No. 4,985,270 disclose non-fat and reduced fat whipped frozen dessert products wherein part or aU of the fat or oil ordinarily incorporated therein are replaced by denatured whey protein particles or particles comprising a core of casein surrounded by a sheU of denatured egg white protein. The patent further discloses the use of the composite egg white protein/casein particles as fat substitutes in sauces, dips, spreads, icing and cream pie fillings.
Carbohydrate-based fat substitutes have been proposed as low cost alternatives to the relatively expensive protein-based macrocoUoid cream substitutes. Singer et al. , U.S. Patents Nos. 4,911,946 and 5,153,020, the disclosures of which are hereby incorporated by reference, disclose fat substitutes which comprise water-dispersible macrocoUoidal particles composed of
carbohydrate materials which particles have a substantially spheroidal shape and specific particle size distributions effective to impart the substantiaUy smooth organoleptic character of an oU-in- water emulsion. These patents disclose carbohydrates that can attain a spheroidal or substantiaUy round shape in the 0.1 to 5 micron diameter size range which are suitable for use as cream substitute ingredients. Starches which occur naturaUy as granules in this size range are suitable for use as cream substitutes and may be treated with cross linking agents to prevent excessive swelling beyond the desired size range. Carbohydrate materials which do not have a natural round shape can be treated by making a solution of the carbohydrate and converting the solution to a gel (typicaUy in a field of high shear-force) so that a narrow distribution of geUed microparticles is formed.
Of interest to the present invention are the disclosures of Spiers et al. PCT PubUcation WO 91/04674 and Spiers et al. PCT Publication WO 91/19424 which relate to alginate and pectin based fat substitutes. The WO 91/04674 pubUcation discloses methods of forming alginate and pectin gels by forming an aqueous mixture of a water soluble or water dispersible alginate or pectin, a calcium ion sequestrant and a sparingly soluble calcium source at low temperature. The mixture is then heated to cause gelation thereof. The WO 91/19424 pubUcation discloses the use of sequestered divalent metal ions such as calcium ions in the production of alginate and pectin microparticulate beads having a size range of from about 15-300 μm for use as fat substitutes. Such fat substitutes are not completely satisfactory because of their relatively large particle sizes, however. Moreover, carbohydrate-based cream substitutes are generaUy inferior to protein-based cream substitutes because they lack the superior functionaUty exhibited by proteins. Accordingly, there remains a desire in the art for improved carbohydrate containing fat substitutes which are characterized by the functionaUty of protein-based cream substitutes and methods for their production.
SUMMARY OF THE INVENTION
The present invention provides improved carbohydrate cream substitutes which are characterized by the functionaUty of protein-based cream substitutes. Also provided are methods for their production. SpecificaUy, water dispersible macrocoUoids are provided which are made up of substantiaUy spheroidaUy shaped particles which may comprise a core of carbohydrate and a sheU of protein. More specificaUy, the macrocoUoids of the invention are made up of substantiaUy non-aggregated macrocoUoidal particles comprising a core of carbohydrate and a sheU of protein wherein the particles have a substantiaUy spheroidal shape and a mean particle-size distribution ranging from about 0.1 microns to 4 microns, with less than 2% of the total number of particles exceeding 5 microns in diameter. The particles are further characterized in that they are effective in a hydrated state to form a macrocoUoid having the substantiaUy smooth organoleptic character of an oU-in-water emulsion. The invention also provides methods of producing the improved fat substitutes comprising forming particles of carbohydrate and coating those particles with a sheU of protein such that the resulting particles are characterized by having a substantiaUy spheroidal shape and a mean particle size distribution ranging from about 0.1 microns to 4 microns, with less than 2% of the total number of particles exceeding 5 microns in diameter. According to one method, the coating step is carried out by treating a mixture of protein and microparticulated carbohydrate having a pH greater than the isoelectric point of said protein with an acid to lower the pH of the mixture to below the isoelectric point of the protein, yet maintain the net negative charge of the carbohydrate. The protein molecules then adopt a positive charge and are attracted to the negatively charged carbohydrate particles with the result that the proteins form a coating on the carbohydrate core.
As yet another aspect of the invention, improved methods of preparing gum-based cream substitutes are provided which comprise the steps of (1) producing a solution of a gum; (2) combining protected ions, preferably sequestered calcium ions, with said solution; (3) placing said solution under high
shear conditions; and (4) releasing said ions to form carbohydrate microparticles under said shear conditions which are selected to form substantiaUy non- aggregated macrocoUoidal particles of carbohydrate having a substantiaUy spheroidal shape from about 0.1 to 4 microns, with less than 2% of the total number of particles exceeding 5 microns in diameter, the particles in a hydrated state being effective to form a macrocoUoid having the substantiaUy smooth organoleptic character of an oU-in-water emulsion. Preferred gums are selected from the group consisting of alginate, geUan and pectin and the resulting carbohydrate particles can be coated with protein in order to produce the preferred carbohydrate/protein cream substitutes of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides improved carbohydrate cream substitutes and methods for the production of same. SpecificaUy, the invention provides water dispersible macrocoUoids comprising substantiaUy spheroidaUy shaped particles which comprise a core of carbohydrate and a sheU of protein which can be used as cream substitutes. The invention also provides improved methods of producing carbohydrate-based cream substitutes. The resulting cream substitutes are particularly useful for producing the core/sheU macrocoUoidal particles of the invention.
The particularly desired organoleptic quaUties of the macrocoUoid materials of the invention are particularly dependent upon the sizes and shapes of the macrocoUoid particles. SpecificaUy, it has been found that dispersions of particles with diameters greater than about 4 microns impart an undesirable chalky mouth feel. The shapes of particles are also important. Particles which are generaUy spheroidal tend to produce a smoother, more emulsion-like organoleptic sensation. Where increased proportions of macrocoUoid particles are generaUy spheroidal or where the macrocoUoid particles are more perfectly spheroidal, it may occur that somewhat greater proportions of particles may have diameters greater than about 4 microns without detriment to the organoleptic character of the macrocoUoid mixture. Particle sizes of about 0.1 microns
contribute a greasy mouth feel which may be objectionable if it is perceived as the dominant tactile characteristic.
According to the invention, cream substitutes are provided which comprise macrocoUoidal particles comprising a core of carbohydrate surrounded by a sheU of protein. Such macrocoUoidal particles can be produced by formation of carbohydrate particles and subsequent enrobbing of those particles with a sheU of protein.
According to methods wherein carbohydrate particles are formed and then later enrobbed with a protein coating, various known methods can be utilized to form carbohydrate particles of the appropriate generaUy spheroidal shape and appropriate size. SpecificaUy, Singer et al., U.S. Patent No. 5,153,020, the disclosure of which is hereby incorporated by reference, teaches various methods for the production of marcocoUoidal carbohydrate particles. Such methods include selection of starches having granules of appropriate sizes and cross-Unking of those granules to prevent excessive swelling upon hydration. Appropriate cross-Unking methods are weU known in the art and include treatment with cross-Unking agents such as phosphates, phosphorous oxychloride and dicarboxyUc anhydrides.
Methods of producing macrocoUoidal carbohydrate particles from sources other than starch granules are also disclosed by Singer U.S. 5,153,020. Other suitable carbohydrates include gums such as algin, pectin and geUan, cross- linked dextran, curdlan, konjac, mannan, chitin, schizophyUan and chitosan. Carbohydrate gels that do not have a natural round shape must be treated so that they attain a substantiaUy spheroidal shape. This can be accompUshed by producing a solution of the carbohydrate and converting the solution to a gel rapidly and uniformly (typicaUy in a field of high shear-force) so that a narrow distribution of geUed microparticles are formed having the above described diameters of between about 0.1 and 5 microns. The apparatus and high shear mixing methods described in Singer et al., U.S. Patent No. 4,828,396, the disclosure of which is hereby incorporated by reference, are particularly useful for producing carbohydrate macrocoUoid particles for use according to the
invention. According to one method, a stream of carbohydrate solution is introduced into a highly turbulent reaction zone where the geUed microparticles are formed. According to another method, calcium alginate macrocoUoidal particles are formed by making a solution of sodium alginate and introducing this solution into a calcium ion containing solution through, for example, an ultrasonic spray nozzle or other device capable of producing droplets less than 5 microns in diameter. Alternatively, a solution of sodium alginate can be introduced into the fluid processor apparatus described in Singer, U.S. Patent No. 4,828,396 and subjected to shearing during administration of a calcium chloride solution to form calcium alginate microparticles. As another example, geUan can be microparticulated by spray cooling a hot geUan solution by means of a device capable of producing droplets less than 5 microns in diameter.
The present invention also provides improved methods for the preparation of gum-based macrocoUoidal particles which can be used as a carbohydrate core to be enveloped by a protein sheU or can be used alone as a carbohydrate cream substitute. While gums such as alginate and pectin can be solubilized and treated by administration of calcium ions to form gels which are simultaneously or subsequently subjected to shear to form microparticles, the present invention provides improved methods for production of such microparticles. Specifically, methods for the production of gum-based cream substitutes are provided according to the steps of (1) producing a solution of the gum; (2) combining protected ions with said solution; (3) placing said solution under high shear conditions; and (4) releasing said ions under said shear conditions which are selected to form substantially non-aggregated macrocoUoidal particles of gum. According to this method, the shear conditions are selected to form substantiaUy non-aggregated macrocoUoidal particles of gum having a substantiaUy spheroidal shape and a mean particle-size distribution ranging from about 0.1 to 4 microns, with less than 2% of the total number of particles exceeding 5 microns in diameter, the particles in a hydrated state effective to form a macrocoUoid having the substantially smooth organoleptic character of an oU-in- water emulsion.
According to the methods of the invention, an aqueous solution is prepared which contains up to 8% by weight of a gum, with or without other gums. The gum preferably comprises sodium alginate, pectin or geUan. The gum solution is then combined with protected ions, which can be calcium or other appropriate ions including but not limited to sodium, potassium, magnesium and the like. The ions may be protected by sequestration, encapsulation or other means known to those of skill in the art. Preferred ions for use according to the methods of the invention are calcium ions. Calcium ions, for example, may be sequestered either by means of a calcium salt which is insoluble (or has very low solubility) at the pH or temperature of the premix, by using a calcium ion sequestrant which can release the sequestered ion upon changing the pH, temperature, or by other methods known to the art. Calcium ions protected by encapsulation may be released by heating. Preferred calcium salts for sequestration of calcium ions include monocalcium phosphate, dicalcium phosphate, tricalcium phosphate, calcium tripolyphosphate, calcium carbonate, calcium caseinate and calcium citrate. Other ions, such as sodium, potassium, magnesium, and the like, may be protected by sequestration, encapsulation or by various methods known to those skUled in the art.
The concentration and nature of the ion used to form the gel can be varied in order to achieve the desired properties of the final microparticle. Depending on the source and type of polysaccharide, the gel microparticle can range in strength from a soft deformable gel to a hard brittle gel. An appropriate ion gelling gum and gel forming ion is thus chosen to achieve the desired properties of the final product. The solution containing the gum and sequestered ions is then placed in a fluid processor device such as that described in Singer, U.S. Patent No. 4,828,396. WhUe the solution is undergoing shear, the ions are released to the gum to form microparticles of the geUed gum either by acidification, heat or other appropriate means. It is postulated that the insoluble sequestered ions act as nuclei upon which the carbohydrate microparticles can form.
Once the carbohydrate macrocoUoidal particles are formed, they must not substantiaUy aggregate further and must preferably remain unaggregated.
The resulting microparticulated cream substitute may then be used as a cream substitute alone or can be further treated with protein according to the methods of the invention to yield a carbohydrate core/protein sheU cream substitute material. The cream substitute may also be dried by lyophiJization, spray drying, drum drying or other suitable means. The resulting dried product can easUy be reconstituted using conventional mixing equipment and will retain its functionaUty. The invention provides methods by which particulated ionic polysaccharide materials such as alginates, pectins, geUan and the like can be combined with a protein such as whey, casein, soy, albumin and other soluble proteins to produce the carbohydrate core/protein sheU macrocoUoidal particles of the invention. The mixture is then titrated with acid to reach a pH at or below the isoelectric pH of the protein component, yet above the isoelectric pH of the carbohydrate component. This results in a reversal of the net charge on the protein, from negative to positive, whUe the carbohydrate component remains unaffected and maintains a net negative charge. The lowering of pH results in an ionic attraction of the protein to the particulated carbohydrate to form a complex comprising a carbohydrate core and a protein sheU. FoUowing this step, the pH may optionaUy be readjusted without disrupting the complex. If protein modification, such as denaturation, is desired, this can be carried out either prior to or after the complexation step. The resulting macrocoUoidal particles can be used as cream substitutes in a variety of appUcations according to the invention. The macrocoUoids of the invention can replace aU or a portion of the fat or cream in food products which typicaUy comprise fat or oU. SpecificaUy, the invention provides improvements in food products containing fat and/or cream, the improvement which comprises: substituting for aU or a portion of the fat and/or cream, a water-dispersible macrocoUoid comprising substantiaUy non-aggregated macrocoUoidal particles comprising a core comprising carbohydrate and a sheU comprising protein, said particles having a substantiaUy
spheroidal shape and a mean particle-size distribution ranging from about 0.1 microns to 4 microns, with less than 2% of the total number of particles exceeding 5 microns in diameter, the particles in a hydrated state effective to form a macrocoUoid having the substantiaUy smooth organoleptic character of an oU-in-water emulsion. The macrocoUoid cream substitutes of the invention typicaUy contain from about 1 to about 20 percent by weight carbohydrate, depending upon the water binding capacity of the specific carbohydrate. Such food products as ice cream, yogurt, pourable and spoonable salad dressings, mayonnaise, cream, cream cheese, natural cheese, other cheeses, sour cream, sauces, dips, icings, whipped toppings, frozen confections, milk, coffee whitener and spreads may be formulated as reduced fat products, benefiting from the hydrated macrocoUoid replacing aU or part of the fat and still providing the desired creaminess.
EXAMPLE 1
In this example, an alginate cream substitute was produced according to an improved method of the invention. SpecificaUy, an aqueous solution containing 2% by weight sodium alginate (Kelgin LV, Kelco Division of Merck, San Diego CA) was prepared and anhydrous dicalcium phosphate (Stauffer Chemical Co. , Westport, CT) was mixed in to the alginate solution to reach a final concentration of 0.15 M. Since dicalcium phosphate is insoluble in water at neutral pH or higher, it forms a dispersion and does not interact with the sodium alginate to any significant extent. The mixture, at pH 8.0, was then placed into a fluid processor device such as that described in Singer, U.S. Patent No. 4,828,396 which had been modified in order to aUow a syringe to inject solutions into the reservoir. WhUe the processor device was subjecting the solution to shear at 5200 rpm, 1 N HC1 was injected in order to lower the pH to 4.7. This caused the dicalcium phosphate to be solubilized and thus interact with the sodium alginate to form calcium alginate microparticulated gel. At this point, a concentrated solution of calcium chloride (for example 6 mol/1) was optionaUy added to the mixture while still under the high shear environment to further adjust
the texture of the particles once they had been formed. After injection of the calcium chloride, the final calcium chloride concentration was 0.045 M. The excess dicalcium phosphate in the final product was removed by treating the solution with a pH 4.5 buffer to solubilize the dicalcium phosphate and then removing the Uquid phase by high speed centrifugation at 22,100 X G (Beckman
Model J2-21 Centrifuge, Beckman Instruments, Inc. Palo Alto, CA). The particles which resulted from this process were spheroidal, between 0.1 and 3 microns in diameter, deformable and exhibited few or weak particle to particle interactions, as determined by Theological measurements. The product was smooth and creamy with no associated chalkiness or grittiness. These particles could be used as a carbohydrate cream substitute alone or could be subjected to further processing to produce the carbohydrate core/protein sheU macrocoUoid particles of the invention.
EXAMPLE 2
In this example, an alginate cream substitute was prepared according to an improved method of the invention. SpecificaUy, a solution of calcium chloride was mixed with trisodium phosphate so that the concentration of each component was 0.3 M. The trisodium phosphate acts as sequestering agent for the calcium ions. To this mixture, sodium alginate (Protanal LF 40, Pronova Inc., Portsmouth, New Hampshire) was added to a final alginate concentration of 2% by weight. This mixture was then placed into a fluid processor device such as that described in Singer, U.S. Patent No. 4,828,396 which had been modified according to Example 1 above. While the processor device was subjecting the solution to shear at 5200 rpm, 12 N HC1 was injected in order to lower the pH to 5.7 and cause the sequestrant to release the calcium ions and thus initiate the formation of calcium alginate microparticulated gel. The remaining sequestrant and other low molecular weight components were removed by diafiltration using an ultrafUtration unit equipped with 100,000 molecular weight cutoff polysulfone membrane (DDS Mini-Lab 10, DDS FUtration, Nakskov, Denmark). The particles which resulted from this process were
spheroidal, between 0.1 and 3 microns in diameter, deformable and exhibited few or weak particle to particle interactions as determined by Theological measurements. OrganolepticaUy this product exhibited a smooth, creamy mouthfeel, where no individual particles can be felt by the tongue. These particles could be used as a carbohydrate cream substitute alone or could be subjected to further processing to produce the carbohydrate core/protein sheU macrocoUoid particles of the invention.
EXAMPLE 3 In this example, an alginate cream substitute was prepared according to an improved method of the invention. SpecificaUy, a solution of calcium chloride was mixed with sodium carbonate so that the concentration of each component was 0.21 M. To this mixture, sodium alginate (Protanal LF 5/40 RB, Pronova Inc., Portsmouth, New Hampshire) was added to a final alginate concentration of 5 % by weight. This mixture was then placed into a fluid processor device such as that described in Singer, U.S. Patent No. 4,828,396 which had been modified according to Example 1 above. While the processor device was subjecting the solution to shear at 5200 rpm, 6 N HC1 was injected in order to lower the pH to 6.1 and cause the sequestrant to release the calcium ions and thus initiate the formation of calcium alginate microparticulated gel. The remaining sequestrant and other low molecular weight components were removed by diafiltration using an ultrafiltration unit equipped with 100,000 molecular weight cutoff poly sulf one membrane (DDS Mini-Lab 10, DDS FUtration, Nakskov, Denmark). The final product was made up of individual calcium alginate particles between 0.2 and 2.5 microns, with an average particle size of 0.8 microns. This product has a clean flavor with a smooth, creamy texture. This material was dried and subsequently rehydrated, resulting in the same particle size distribution and functionaUty as before drying. These particles could be used as a carbohydrate cream substitute alone or could be subjected to further processing to produce the carbohydrate core/protein sheU macrocoUoid particles of the invention.
EXAMPLE 4 In this example, a pectin cream substitute was prepared according to an improved method of the invention. SpecificaUy, a solution of calcium chloride was mixed with sodium carbonate so that the concentration of each component was 0.21 M. To this mixture, pectin (OM-601 Herbstreith & Fox,
Neuenburg/Wurtt, Germany) was added to a final concentration of 2% by weight. This mixture was then placed in a fluid processor device such as that described in Singer, U.S. Patent No. 4,828,396 which had been modified according to Example 1 above. While the processor device was subjecting the solution to shear at 5200 rpm, 6 N HC1 was injected in order to lower the pH to 6.1 and cause the sequestrant to release the calcium ions and thus initiate the formation of calcium pectate microparticulated gel. The remaining sequestrant and other low molecular weight components were removed by diafiltration using an ultrafiltration unit equipped with 100,000 molecular weight cutoff polysulfone membrane (DDS Mini-Lab 10, DDS Futration, Nakskov, Denmark). The average particle size of this product was 1.2 microns. This product had a smooth, creamy mouthfeel, with Uttle or no grittiness. These particles could be used as a carbohydrate cream substitute alone or could be subjected to further processing to produce the carbohydrate core/protein sheU macrocoUoid particles of the invention.
EXAMPLE 5 According to this example, microparticulated calcium alginate was coated with whey protein to produce a carbohydrate core/protein sheU macrocoUoid according to the invention. SpecificaUy, a 7:3 volume fraction of microparticulated calcium alginate produced generaUy according to the method of Example 3 and Uquid whey protein concentrate was made by adding 9.5 Kg of Uquid whey protein concentrate (42% soUds; 53% protein, dry basis) to 22.2 Kg of the microparticulated calcium alginate (2 % soUds). The mixture, which had a pH of 6.33 at mixing, was treated with 1 N HC1 to lower its pH to 4.23 which was below the isoelectric pH of the whey protein. The lowering of pH
reversed the net negative charge on the whey protein to a net positive charge with the result that the whey proteins were attracted to the negatively charged microparticulated calcium alginate particles forming a protein coating on those particles. The mixture was then treated with 1 N NaOH to raise the pH to 6.53 and the mixture was then heated to 95°C in order to denature the whey protein sheUs. The final product had the mouthfeel and flavor profile simUar to Simplesse® 100, an aU whey protein fat substitute disclosed in U.S. Patent Nos. 4,734,287 and 4,961,953. Transmission Electron Microscopy revealed the presence of microparticles comprising carbohydrate and protein less than one micron in diameter but did not indicate the presence of any microparticles comprising only protein. Zeta potential measurements, probing the particle surface, indicate that the carbohydrate cores are enrobbed by the protein sheU. This material was dried and subsequently rehydrated, resulting in the same particle size distribution and functionaUty as before drying. Numerous modifications and variations in the practice of the invention are expected to occur to those skUled in the art upon consideration of the foregoing description of the presently preferred embodiments thereof. Consequently, the only limitations which should be placed upon the scope of the present invention are those which appear in the appended claims.